We have a custom IMX8MM board with a 4GB eMMC chip connected.
The eMMC does not initialize in u-boot and fails at CMD8.
Can you suggest a possible solution ?
Following is the error log with eMMC debug messages enabled:
u-boot=>
u-boot=>
u-boot=>
u-boot=> mmc dev 2
.....
.....
.....
mmc_power_cycle [2785] ret 0
mmc_power_cycle [2790] ret 0
mmc_power_on [2760] Cannot control power
CMD_SEND:8
ARG 0x00000000
esdhc_send_cmd_common - 487 USDHC
RET -70
mmc_init: -70, time 268
u-boot=>
u-boot=>
u-boot=>
Thanks for your support,
Thanks and regards,
Nishad
Solved! Go to Solution.
Hello Igor,
The issue has been resolved. There was a mismatch between processor and eMMC power supplies. After connecting compatible power supplies, the eMMC gets initialized.
Thanks for your continued support.
Regards,
Nishad
Hi nishadkamdar
from log :
"mmc_power_cycle [2785] ret 0
mmc_power_on [2760] Cannot control power"
issue may be related to swtiching emmc to some high speed mode, like HS200
which requires power cycling and 1.8v signalling. One can try this emmc with some
board with emmc, like i.MX8M EVK and check signals on both cases.
Best regards
igor
Thanks for the reply, but as per the log and our observation, the CMD8 fails when invoked for the 1st time.
At this point the host frequency is 25MHz that is not high speed mode. This error is seen before a command to switch to the high speed mode is sent to the eMMC device.
Hi nishadkamdar
you can attach logic analyzer and check where error happens, use eMMC
specification as reference. Per sect.A.6.2 Switching to high-speed mode :
for switching to HS200 mode .. these steps after the bus is initialized :
- Send CMD7 with the Device’s RCA to place the Device in tran state
- Send CMD8, SEND_EXT_CSD. From the EXT_CSD the host can learn the
power class of the Device, and choose to work with a wider data bus
Also BSP version might be the problem as reported on
Best regards
igor
Hello Igor,
The issue has been resolved. There was a mismatch between processor and eMMC power supplies. After connecting compatible power supplies, the eMMC gets initialized.
Thanks for your continued support.
Regards,
Nishad